Eight older horses are expected to duel in Saturday's $200,000 Richter Scale Breeders' Cup Sprint Championship (gr. II) at Gulfstream Park. The Michael Gill-owned, Mark Shuman-trained entry of Native Heir and Highway Prospector will likely go off as the favorite in the seven-furlong sprint. The entry is 9/5 on the morning line.In his last out, Native Heir, a 5-year-old son of Makin, won the Deputy Minister Handicap (gr. III) by 4 1/2 lengths. His time of 1:15 for the 6 1/2 furlongs tied Gulfstream Park's track record for that distance. Highway Prospector, a 6-year-old sonof Crafty Prospector, has won all his three starts at Gulfstream this winter with strong stretch rallies.Shuman has named Cornelio Velasquez to ride Native Heir, one of the starting highweights at 116 pounds, while Jose Santos will try for four straight wins aboard Highway Prospector, 114.Installed at a close second choice at 5-2 on the morning line is Harold Queen's Burning Roma, also in at 116. The 5-year-old son of Rubiano has won 11 of 24 career starts and comes off a victory at Tampa Bay in his first turf start.Trainer Heather Giglio has named Eibar Coa to ride Burning Roma.Also expected to start in the Richter Scale are: Tour of the Cat; Binthebest; Smooth Jazz; Fire and Glory; and Ticket to Freedom.